Best bolts for jackplate to motor?

[WATERWINGS]

I got a set of 2" spacers to add to my 8" jackplate on the 'Shot, and I need to get some 5" bolts to connect them all together.

I can get SS bolts from Lowes here in town, but do I need to get something above "just normal" SS bolts??

[jphii]

Grade 8 SS or above would pobably be the ticket.

[Lockjaw]

Yeah you need grade 8. DO you have an Ace Hardware or something in your area? Also make sure you have poly lock nuts too.

[Ziemer]

All of mine are fine thread too, rather than the coarse thread you can get at Lowes.

[vector mike]

Be sure to use some kind of lubricant on the threads with the bigger diameter bolts. Sometimes they will "gall" when you have alot of SS rubbing on each other and you won't get them apart. I found out the hard way. :o

[WATERWINGS]

Yea,

We have Lowes, Home Depot, and Ace here in town.

I don't know what length they have them in, or what grade they are.

If I go to the Marina, (or local boat dealers) I'm sure they will have what I want, but, I am sure that they wont be cheap.

[Gordie Miller]

OEM Merc bolts (1/2-20 SS) and nuts (brass nylock), full set of 4 with washers, $30.00 TYD. 847-830-8061.

[inspectorlance]

so are we saying that standard hardware store SS bolts are ok? , or should we have grade 8 ? does stainless come in grade 8 ?? is stainless graded different ? mine just say S30400 THE. whats the difference ???

Lance

[vector mike]

Don't hollar at me too loud but mine are from the local hardware store. I've used and reused them for a number of years now. Don't know if there is a grade difference on SS bolts.

[WATERWINGS]

I'll wait around for a few days to see how this one pans out.

There ARE different grades of stainless just like there different grades of Titanum.

In stainless there is 304, 304-L, 316, 309 etc.

Don't know it that is strength difference, but there is a corrosion difference, but that wouldn't count for how we use them.

[Alan Power]

Grade 8 bolts don't come in SS.

[transomstand]

I looked at this last year. The strength difference in stainless grades is negligable. They are all about Grade 5. If you can go waaay back in the archives, there were some really long threads about bolts, with some pretty major arguments.

Pete

[SportJ-US-1]

Look under fasteners in the yellow pages. One of the major suppy stores will fix you up with whatever you need. The standard OEM mounting hardware is not good enough for jackplates and setbacks. The leverage (read stress) is increased up to 10 times depending on setback and lift. You also need plates on the inside of the transom if you don't already have them.

[Alan Power]

Some info on bolts and materials...

http://www.boltdepot.com/fastener-information/Materials.aspx

http://www.boltdepot.com/fastener-information/Bolt-Grade-Chart.aspx

http://www.hudsonfasteners.com/fast_guide/fg_grade_markings.htm

[Gordie Miller]

is partially right, the loads are increased with setback, HOWEVER, the load is increased primarily on the bolts holding the jackplate to the boat, NOT the bolts holding the motor to the jackplate. It is a simple mathmatical equation(a lever point). Grade 8 or better is the best way to go for strength, however they will need to be changed as they corrode and weaken over time(varies depending on environment). If you do go with grade 8, you MUST buy gr 8 nuts AND washers to compliment the bolts, your chain is only as strong as the weakest link(hardware store nuts and washers)coupled with gr 8 bolts is pointless. The difference in stainless grades, as noted above, is primarily dealing with the corrosion resistance of the material and very little to do with strength.

[transomstand]

Anyone have experience with these? They sound like the best of both worlds.

<TABLE cellSpacing=10 width="100%"><TBODY><TR><TD class=PresentationHd colSpan=7>Grade 8 Ultra Corrosion-Resistant Coated Alloy Steel http://www.mcmaster.com/catalog/112/gfx/small/cads.gif (http://javascript<b></b>:CADHelp();)</TD></TR><TR><TD vAlign=top width="10%" colSpan=2></TD><TD vAlign=top width="24%" colSpan=2><TABLE><TBODY><TR><TD align=middle>http://www.mcmaster.com/catalog/112/gfx/small/91286ac2s.gif (http://javascript<b></b>:chgimg(8);)</TD></TR><TR><TD align=middle>Fully Threaded†</TD></TR></TBODY></TABLE></TD><TD vAlign=top width="66%" colSpan=3 rowSpan=2>These screws have a clear silver, water-based inorganic coating (also known as armor coat) for excellent corrosion resistance. They are effective replacements for stainless steel cap screws. The coating has a salt spray resistance of 1000 hours per ASTM B117 (zinc-plated screws show rust at less than 200 hours). Coating does not affect the function of the thread.
Screws are made of high-strength alloy steel. They meet SAE J429. Rockwell hardness is C33-C39. Minimum tensile strength is 150,000 psi. Screws have a Class 2A thread fit and are grade marked on top of the head (six radial lines indicate Grade 8). Length is measured from under head. For ultra-coated nuts, see 93827A on page 3026 (http://javascript<b></b>:document.FrameworkASP.CtlgPgNbr.value='3026';document.FrameworkASP.CtlgEdition.value='112';document .FrameworkASP.ReqTyp.value='CATALOG';document.FrameworkASP.submit();); for washers, see 98180A on page 3052 (http://javascript<b></b>:document.FrameworkASP.CtlgPgNbr.value='3052';document.FrameworkASP.CtlgEdition.value='112';document .FrameworkASP.ReqTyp.value='CATALOG';document.FrameworkASP.submit();). Screws indicated with a † are always fully threaded (fully threaded screws are also known as tap bolts).

</TD></TR></TBODY></TABLE>
They are sold by Mcmaster-Carr www.mcmaster.com (http://www.mcmaster.com)

[QUICKSILVER]

Regardless of what the bolts were made of, or the grade. How many people here have had an engine mounting bolt fail, and what was it made of? All of the factory built jack plates, I have owned, came with stainless bolts. Has anyone lost an engine from the bolts failing?

[Ted Stryker]

In my opinion, a decent 5 grade 1/2" fastener is the strongest thing back there... Really, how strong is a few peices of fiberglassed plywood compared to the strength of a 1/2 SS bolt or the bolting flanges of a cast aluminum clamp bracket... Even a 1/4" x 20 bolt is rated for over 1,000 lbs. tensile with proper installation... I know that a 1/4 x 20 is no where near strong enough, it's just for perspective... Four 1/2 x 20 grade 5 fasteners can lift a D3-D4 bulldozer off of the ground, can your transom do that..? As long as your fasteners ( at least grade 5 ) are in good shape, go for it... Personally I like them both when properly installed, the grade 8's are nice for the jackplate to hull fasten because I don't have to retorque them like SS, and I don't run in salt water and I always use anti-seize...

[BUSHWACKER]

www.aircraftspruce.com (http://www.aircraftspruce.com), order from local hardware store, www.bobsmachine.com (http://www.bobsmachine.com), www.arp.com (http://www.arp.com), www.ebay.com (http://www.ebay.com) ,do search on computer
I hade a bit*h of a time finding nutserts, and a 1/4'' rivit gun, been there done that:D
My Momma tol me, ya gotta shop around.

[oldgeezer]

I just mounted a 2 1/2 set back plate and 5 1/2 CMC hydraulic JP to my Stratos with a Mercury 250 EFI weighing approx 500 lbs. The manufacturer(CMC) indicated the bolts needed to be 18-8 Stainless at 1/2 inch diameter with SS washers and stainless lock washers. In addition to these specific bolts, they also had a specific torque applied to both the set back plate and JP. Hope that this helps.